322 
ON THE VIGOROUS GROWTH OF FOREIGN SEEDS. 
said to account for the results above alluded to, is become questionable ; 
a new theory has been advanced to account for the fact, that plants 
get tired ” of growing on the same spot. The author of “ The 
Domestic Gardener’s Manual,” and a chemical philosopher in France, 
M. Macaire, ascertained, about the same time, that plants exude a dele¬ 
terious refuse or excrement from their roots, which is offensive to all 
other plants of the same genus. The authors of this idea have reason 
on their side, inasmuch as the water or earth in which a plant has been 
nourished contains, after the plant is removed, some faecal matter 
belonging to the prepossessing crop; but as to how much, or in what 
way, the discharges from the preceding are noxious to the succeeding 
crop, has not yet been fully explained; nor has it yet been fairly 
proved whether the exhausting operation of the former crop, or its 
noxious exudations, be the discouraging circumstances to the following; 
but we would say to cultivators, that it is either the one or the other— 
perhaps both; and therefore it is well to keep to the axioms relative to 
a change of seed which experience has established. 
It really appears that plants, like animals, are not only benefited by 
a change of soil, but by a change of air. If an old stunted pear or 
apple tree, which has stood in an old garden for years without increas¬ 
ing in bulk or showing any signs of healthy expansion, be removed to 
a fresh station out of the garden, or to a place a mile or two distant, it 
is immediately renovated, and thrives exceedingly. This and many 
other similar instances which might be quoted, show clearly that fresh 
soil and a new place have some unaccountable effect upon the dormant 
energy of such a plant. We know that in the act of removal many of 
the old and stunted roots are broken and dismembered ; and from the 
wounded parts fresh and more numerous roots will be produced, which, 
together with perhaps a little pruning of the head, generate a new 
vigour, which can only be attributed to the development of the new 
members. The soil of the new may be exactly like that of the old 
station; and the quality of the air at a few yards, or even a few miles 
distant, cannot be supposed to be so different as so sensibly to affect 
plants exposed to it : we must therefore conclude, that it is not to the 
change of air, but to the disturbance and manipulation sustained by the 
plant in its removal, that we must attribute its reinvigoration. 
As this greater vigour presented by foreign seeds or plants is so con¬ 
stantly an occurring circumstance, it behoves us not to be deceived by 
it, as in certain cases we may be. The planter who has heard of a cer¬ 
tain new variety of potato raised in some distant place, immediately 
sends for a sack of the new sort; they turn out wonderfully prolific the 
first and perhaps the second year. He cries them up to the skies ; but 
in the following years the kind begins to fall off in estimation, and is 
